What goes wrong when you ignore that capacity buffers?

The most common reason fails: Treating buffer time as available time. The moment you see empty space on your calendar and fill it with a low-priority task or an optional meeting, the buffer ceases to exist. The point of a buffer is that it looks unproductive. It looks like slack. And the temptation — especially for high-achievers who equate busyness with value — is to eliminate that slack the instant it appears. This converts your buffer back into committed capacity, and the next unexpected demand finds you right back at 100% utilization with no room to absorb it.

The fix: Open your calendar for the coming week. Count the total hours currently scheduled with specific commitments (meetings, deep work blocks, appointments, calls). Divide that by your total available working hours. If the ratio exceeds 85%, identify the lowest-priority commitments and move them to a tentative or optional status until your scheduled-to-available ratio drops to between 70% and 85%. Block the freed hours as "Buffer — Do Not Schedule" and defend them for one full week. At the end of the week, note how many buffer hours were consumed by genuine unexpected demands versus how many remained available for recovery or opportunistic work.

The underlying principle is straightforward: Reserve some capacity for unexpected demands — running at 100% leaves no room for surprises.